Patent GB-529505-A (GB)
Title: Percussion fuzes for aerial bombs
IPC: F42C1/08
Filed: 1939-02-17
Abstract: 529,505. Bomb fuzes. AKTIEBOLAGET BOFORS. Feb. 17, 1939, No. 5395. Convention date, Feb. 17, 1938. [Class 9 (i)] A percussion fuze for aerial bombs which are rotated as they fall. is provided with two priming mechanisms, each having a centrifugal safety device and a transport safety device, one of the priming mechanisms being arranged in one form of the invention to cause explosion on impact of the bomb without delay and the other with delay. In another form, one of the priming mechanisms can be set to act with adjustable delay or without delay, and the second mechanism gives mechanically-retarded ignition, i.e., explosion occurs only when the bomb comes to rest. In either form, both mechanisms may be armed independently or simultaneously. In the latter case, the delay-action mechanism operates when the bomb penetrates a relatively non-resisting target, while the direct action or the retarding mechanism acts on impact if a hard object is struck. The fuze assembly is arranged in each case in the side of the bomb B. In the construction shown in Fig. 1, which illustrates the non- delay mechanism of the first form, each transport safety comprises a spring-loaded pin 14 which, through an intermediate pin 15, immobilises a centrifugal bolt 16. Before the bomb is released, the cover 10, Fig. 6, of the transport safety device is removed and the end of a cord 11 attached to the aircraft. When the bomb has fallen the necessary distance, the pin 14 is released by the withdrawal of the lower end of the cord 11 from the path of a ball 13, and the bolt 16 is thus freed. Due to rotation of the bomb, the bolt 16 is moved outwardly by centrifugal force from engagement with the striker 3, thus arming the fuze. Upon impact, the striker is driven by its momentum on to the primer 4, compressing its spring 18, and the flame passes through free passages 6, 7, to the detonator 5. The delay mechanism is similar in construction to the non-delay mechanism, but the flame passes to the detonator by way of passages 6<SP>1</SP>, 8, 9, 7. Fig. 4, containing a delay composition. 'Figs. 7 and 9 show, respectively, the adjustable-delay and the mechanically-retarded mechanisms of the second form. The centrifugal bolt 22, Fig. 7, is a spring-loaded plunger mounted within an outer member 19, and is so arranged that the hammer 23 is kept at " safe if the transport safety 10 is removed, and the fuze receives an accidental blow. Arranged between the primer 30 and the detonator 5 is a non-rotatable ring 32 formed with a channel 33 filled with fuze composition, and an opening 34 communicating with the primer. Associated with the ring 32 is a rotary disc 35 which is provided with a through opening making communication between the underside of the channel 33 and the detonator 5, and the period of delay is varied by rotating the disc to alter the angular distance between the opening 34 in the ring 32 and the opening in the disc 35. The retarded ignition mechanism, Fig. 9, comprises a sleeve 43 carrying the primer, which sleeve is driven forward on impact compressing a spring 48 and releasing one or more locking balls 49, whereupon the spring 48 returns the primer against the firing pin 41. The flash passes through passages 50, 51 and one or more of several passages 53 through the disc 35, to the detonator 5.